Nothing wrong with the car, its you! If you would just drive along at 45 mph with A/C off and never stop you will get 19 MPG.
Actually that rating is a comparison rating. The manufacturers will run their vehicles thru a preprogrammed set of mileage tests on a "real life like road test" thru city and highway conditions which dont include warm up cycles and traffic congestion. I used to do mileage tests at the Linc/Merc dealership which consisted of preset speeds to verify what the maximum mileage a car could get. I could get 34 MPG in Lincoln Town Car any day of the week, but that was only after the vehicle was warm and if I hit any traffic lites I would have to start the test over again to get the mileage verification of 34 MPG. That test is to confirm what the vehicle is capable of getting and that is how that 19 MPG rating on your truck is compiled. AND ... the government just goes along with that.... cuz their stupid and they are the government!
The oxygen sensors before the cats are normal 02 sensors that tell the PCM what the engine is doing and cycle at a high rate of speed. The sensors behind the cat are the cat monitor sensors that cycle much slower if the cats are good. When you have a bad cat the rear sensors operate at about the same rate as the front ones and that tells the PCM to set the check engine lite because of the bad cat. If there is even a minor problem in the system the lite will come on and the PCM will set a code. With no lite on, the system is operating within acceptable parameters, which are very narrow in todays cars.
Last edited by 2-manytoyzs; 01-06-2005 at 11:45 PM.